Recursion - Multimedia Introduction to Programming Using Java - page 425

point (x2, y2) is (x1+dx/3, y1+dy/3) .
point (x4, y4) is (x1 + 2 * dx / 3, y1 + 2* dy / 3) .
point (x3, y3) is ((x1 + x5) /2+p*(y1-y5),
(y1+y5)/2+p*(x5-x1)) .
Points (x2, y2) and (x3, y3) are easy to figure out. The calculation of (x3,
y3) is harder; it rests on trig and the fact that all four lines are the same length.
Once procedure drawFlakeLine is written, we suggest that you put it in a
subclass of JFrame or JPanel along with static constants that give the coordi-
nates (xtop,ytop) , (xleft, yleft) , (xright, yright) of an equilateral tri-
angle and a variable K and then write this method paint :
/** Draw a Koch snowflake of order K by drawing three Koch lines of order
K from (xtop, ytop) to (xleft, yleft), (xleft, yleft) to
(xright, yright) , and (xright, yright) to (xtop, ytop) */
public void paint(Graphics g)
Figure out suitable values for the points of the main equilateral triangle by exper-
iment.